This invention relates to a steering device for paved surface cleaners of the self-propelled variety with no fixed steering or driver's station.
As is known, there are available on the market, and currently manufactured by the Applicant, machines for washing clean and drying the floors of warehouses, sheds, commercial establishments, and more generally, large surface area floorings. Such machines are commonly referred to as auto-scrubbers.
These are machines relatively compact in size which can poke into the narrowest corners of a storehouse, for example. They include a frame supporting a reservoir of clean washing water, a reservoir for foul regain water, clean water delivery members and foul water suction members, rotary brushes which are constantly wet with washing water, drive motors for said brushes, and at least one floor-wiping blade lying across the machine direction of travel and set rearwards of the brushes.
Being intended for cleaning large surfaces and to be a work implement proper, the machines in question are made self-propelled and equipped with a specific steering device. The steering device, moreover, is to provide highly responsive and effective steering control, because such machines are also to be driven along twisting and irregular paths.
However, such machines, or at least the most compact among them, owing to their small overall size, lack any fixed driver's compartment or steering station for the operator including a rest seat. The operator is to control the machine in a standing posture while walking behind it.
In view of the foregoing, it will be appreciated that the machine cannot be operated by means of pedal controls on a substantially continuous basis, since the operator's feet would be distracted therefrom.
Nor does the use of ordinary steering wheels appears to be appropriate or convenient, given that these devices only afford prompt control of the steering action proper and no forward and reverse running control, both hands of the operator being kept busy handling it.
It should be also considered that, with such relatively compact size machines for steering by a walking operator, it is not unusual for some movements to involve the operator's brawn, in order to impart rough travel path corrections. Steering wheels compel the operator to keep his hands close together in one machine area from where shifting by force and purely manual position corrections are difficult to apply.
Accordingly, it is common practice to provide, for controlling such machines, steering devices based upon the use of two handle levers set well apart on the rear side of the machine, in front of the walking operator behind it.
Each handle lever is positioned close to a fixed grip standing proud of the machine at a location from where the machine movements can be conveniently hand controlled.
In this case, the operator can leave the handle levers, if necessary, and presently seize said grips in the event that movements by hand become unavoidable.
The provision of two separate handle levers also enables actuation of a number of controls by hand only.
For these reasons, the Applicant has been manufacturing such type machines as are equipped with steering devices based on operation of two discrete handle levers.
There exists, however, with said handle levers the engineering problem of combining and arranging the various controls, both at the level of the handle levers and downstream thereof, for them to be simple and effective, and accordingly, easy to use and responsive and reliable in their actions.
It should be noted that the machines in question are sometimes operated by relatively unskilled personnel, and that it is therefore important, from the standpoint of safety as well, that the controls be kept simple and efficient.
The state of the art provides for shifting the handle levers toward the machine body to control forward travel, whereas shifting them away from the machine body controls reverse direction travel. Also, either levers have an articulated portion facing up in the inoperative position, on bending which parallel with the machine body, selective braking of the driving wheels is controlled via appropriate wire cables to drive the machine along a bending path.
Rotation of each articulated portion is to be effected toward the other lever, or inwards of the machine outline, to avoid hazardous protrusion while manoeuvering.
In other words, the operator walking behind such a machine turns the articulated portion of the left-hand lever rightwards, from his standpoint, to tension a wire cable braking a left-hand driving wheel, or turns the articulated portion of the right-hand lever leftwards to tension a wire cable braking a right-hand driving wheel. These manoeuvers respectively result in the machine turning to the left and the right.
That steering device, while being suitable for steering said machine types, still has drawbacks.
In fact, the movements that an operator is to perform in order to drive along a non-linear path are hardly natural ones and; above all, are far-reaching and tiring ones; the articulated portions of the handle levers must be constantly bent to selectively brake the driving wheels. Furthermore, relatively complex and easily inaccurate movements are required to both steer and speed up or slow down. The operator's fatigue due to such extensive and continued movements, and the likely inaccuracy of same on the occasion of complicated manoeuvers, may be a potential hazard for bystanders as well as for objects lying close to the cleaner path of movement.